Method and installation for screening and drying strand material upstream of a distribution machine in the course of manufacturing wood material boards

Abstract

A method and an installation or machine for screening and drying strand material. The strand material still in the moist state is screened with a screening device into at least two different fractions of strand material. At least one of the screened fractions is fed to at least one dryer, and the feeding of the strand material to the dryer is carried out by means of a conveying device, which is controlled by a control unit. The control unit assures a uniform, predetermined weight and/or volume input into the dryer(s) by measuring the mass and/or the weight per unit area of the strand material by means of a measuring device.

1 . A method for screening and drying moist strand material, comprising:
 screening, with a screening device located upstream of a distribution machine in the course of manufacturing wood material boards, the moist strand material into a plurality of fractions, the moist strand material of a first fraction being sized differently than that of a second fraction;   conveying the first fraction on a conveying device controlled by a control unit, wherein the control unit is coupled to a measuring device that measures at least one of mass per unit area of the first fraction and weight per unit area of the first fraction; and   feeding the first fraction into a first dryer.   
     
     
         2 . The method of  claim 1 , wherein the measuring device comprises at least one of a weight per unit area scale and a transirradiation device. 
     
     
         3 . The method of  claim 1 , wherein the conveying device comprises a conveyor belt coupled to a drive, and wherein the conveyor belt conveys the first fraction into the first dryer at a speed of the conveyor belt, and wherein the speed of the conveyor belt can be adjusted by the drive. 
     
     
         4 . The method of  claim 1 , wherein the conveying device comprises a metering bin, wherein the metering bin is coupled to a drive and includes a discharge belt, and wherein the discharge belt conveys the first fraction into the first dryer at a speed of the discharge belt, and wherein the speed of the discharge belt can be adjusted by the drive. 
     
     
         5 . The method of  claim 1 , wherein the control unit controls an amount of moist strand material screened into each of the plurality of fractions. 
     
     
         6 . The method of  claim 1 , further comprising storing the moist strand material in a storage bin upstream of the screening device. 
     
     
         7 . The method of  claim 1 , wherein the moist strand material upstream of the screening device comprises short flakes, long flakes, and fine material. 
     
     
         8 . The method of  claim 1 , wherein the screening device comprises a roller screen. 
     
     
         9 . The method of  claim 1 , wherein the screening device comprises a Quadradyn screen. 
     
     
         10 . The method of  claim 1 , wherein a flap control system is coupled to the control unit and the screening device, and wherein the flap control system controls the amount of screened moist strand material contained in each fraction. 
     
     
         11 . The method of  claim 1 , further comprising:
 drying the first fraction in the first dryer, wherein the moist strand material becomes dried strand material;   extracting the first fraction of dried strand material with a “poor” cyclone.   
     
     
         12 . The method of  claim 1 , further comprising:
 drying the first fraction in the first dryer, wherein the moist strand material becomes dried strand material;   conveying the dried strand material into a dry chip storage bin; and   feeding the dried strand material to a distribution station.   
     
     
         13 . The method of  claim 1 , wherein the screening device screens the moist strand material into three fractions, wherein the three fractions are an ultrafine fraction removed from the manufacturing process, a medium fraction used to form center layers of a mat of strand material, and a coarse fraction used to form cover layers of the mat of strand material. 
     
     
         14 . The method of  claim 1 , wherein each of the plurality of fractions of moist strand material is conveyed to a separate dryer. 
     
     
         15 . An installation for screening and drying moist strand material, the installation located upstream of a distribution machine for manufacturing wood material boards, comprising:
 a screening device located upstream of a first dryer and configured to screen the moist strand material; and   a conveying device connected to a control unit and located between the screening device and the first dryer, wherein the control unit comprises a measuring device configured to measure at least one of mass per unit area of moist strand material and weight per unit area of moist strand material.   
     
     
         16 . The installation of  claim 15 , wherein the measuring device comprises at least one of a weight per unit area scale and a transirradiation device. 
     
     
         17 . The installation of  claim 15 , further comprising:
 a moist storage bin located upstream of the screening device and coupled to a discharge device; and   a flap control system coupled to the screening device,   wherein the conveying device is coupled to a drive, and   wherein the control unit is connected to at least one of the drive, the discharge device, and the flap control system.   
     
     
         18 . The installation of  claim 15 , wherein the screening device comprises a Quadradyn®-like classifying device. 
     
     
         19 . The installation of  claim 15 , wherein a “poor” cyclone is located downstream of the first dryer.